The present invention relates generally to lasers. More specifically, the present invention relates to an integrated high-power semiconductor laser.
Telecommunications is a large and fast growing industry. This growth has been enabled, at least in part, by the use of optical amplifiers to extend the range of long-haul optical transmission and by the deployment of Dense Wavelength Division Multiplexing (DWDM) systems to increase the optical channel capacity. These technologies have been improved by extending the bandwidth of Erbium-Doped Fiber Amplifier (EDFA) optical amplifiers from about 20 nm to about 80 nm.
A technical challenge in extending the bandwidth of EDFAs has been the need to provide enough gain in the EDFAs over the entire bandwidth. This can be accomplished by single-mode 980 nm or 1480 nm laser pumps with output powers on the order of 1 Watt or more. Known laser pumps for EDFAs are single-mode semiconductor narrow-stripe pump lasers limited to about 150 mW in a single-mode fiber. This limitation is due to catastrophic optical damage that can occur if the optical power density at the facet of the laser exceeds about 1 to 2xc3x97107 W/cm2 and due to the fact that stripe laser is narrow (e.g., 3-5 xcexc) to ensure single-mode operation.
To overcome the limitation relating to the optical power density, the cross-section area of the laser""s active region must be widened to reduce the power density in the laser stripe (i.e., the active region), especially at the facet of the laser. Widening the cross-section area of the laser""s active region, however, conflicts with the design constraint of single-mode operation. Thus, a need exists to extend the output power of laser pumps for EDFAs beyond the current limit (i.e., 150 mW) by widening the cross-sectional area of the laser while maintaining single-mode operation.
A single-transverse-mode laser has a resonance cavity with an output end. A gain medium portion is disposed within the resonance cavity. The gain medium portion includes an active portion. A mode expander portion is disposed within the resonance cavity between and operationally coupled to the gain medium portion and the output end of the resonance cavity. A single-mode waveguide portion is disposed with the resonance cavity between and operationally coupled to the mode expander portion and the output end of the resonance cavity. The single-mode waveguide portion is a passive portion. The gain medium portion, the mode expander portion and the single-mode waveguide portion are integrally formed.